1. Field of the Invention
The present invention relates to an exposure device, and particularly to an exposure device which exposes a photosensitive material with a light beam which is modulated by a spatial light modulation device in accordance with image data.
2. Description of the Related Art
Heretofore, various exposure devices have been proposed which carry out image exposure with light beams which have been modulated, using spatial light modulation devices, in accordance with image data, such as, for example, exposure devices for photo masks which are employed in liquid crystal fabrication devices, exposure devices for printing plate fabrication and the like.
An exposure device which uses a digital micromirror device (DMD) as a spatial light modulation device has been structured by, for example, a light source 1, a lens system 2, a DMD 3 and lens systems 4 and 6, as shown in FIG. 9A. The light source 1 irradiates laser light. The lens system 2 collimates the laser light irradiated from the light source 1. The DMD 3 is disposed substantially at a focusing position of the lens system 2. The lens systems 4 and 6 focus the laser light, which has been reflected from the DMD 3, onto a scanning surface 5. The DMD is a mirror device in which numerous micromirrors, which alter angles of reflection surfaces thereof in accordance with control signals, are arranged two-dimensionally on a semiconductor support of silicon or the like. In this exposure device, the laser light is modulated by ON-OFF control of each of the micromirrors of the DMD 3 from an unillustrated control apparatus, by control signals which are generated in accordance with image data or the like, and image exposure is carried out with the modulated laser light. Note that FIG. 9A is an unfolded schematic view along an optical axis.
In such an exposure device, for example, with the goal of reducing spot diameter and raising resolution, a microlens array (MLA) 8 may be disposed so as to correspond with an image of the DMD 3, as shown in FIG. 9B, and image exposure with a high resolution may be carried out. Note that, in FIG. 9B, the laser light that has been irradiated from the light source 1 and collimated at the lens system 2 is reflected at a total internal reflection (TIR) prism and illuminated to the DMD 3. Further, the laser light that has been reflected at the DMD 3 passes through the TIR prism and is incident at the lens system 4.
However, in an exposure device which is equipped with a confocal optical system which condenses light reflected from a DMD by lenses of a microlens array (MLA), passes the light through apertures and focuses the light, even if optical axis adjustment is carried out at a time of assembly, relative mispositioning between structural members arises because of thermal expansion of the structural members, chronological development of residual stresses in the structural members and the like, and there is a problem in that images on the DMD are not accurately projected to a focusing plane. Further, as a result thereof, there are problems in the exposure device in that utilization efficiency of light falls, focusing positions are shifted, and light spills over into neighboring pixels and causes a deterioration in resolution.